Method of making esters of glycols



Patented Nov. 19, 1935 PATENT OFFICE 2,021,852 METHOD OF G ESTERS FGLYCOLS Gerald H. Coleman and Garnett V. Moore, Midland, Mich, assignorsto The Dow Chemical Company, Midland, Mich, a corporation of Michigan NoDrawing. Application May 5, 1932, Serial No. 609,494

14 Claims.

, The present invention concerns an improved method of making an esterof a glycol, particularly ethylene glycol diacetate, through reacting analkylene dichloride with an alkali metal salt of an aliphatic acid inthe presence of a catalyst.

A number of previous workers have prepared ethylene glycol diacetatethrough reacting ethylene dichloride with an alkali metal acetate,

but the reaction, as ordinarily carried out, yields a difiicultlyseparable mixture containing not only ethylene glycol diacetate, butconsiderable quantities of by-products, e. g. ethylene glycol, ethyleneglycol monoacetate, etc.

Meyer, in German Patent No. 332,677, has

shown that when anhydrous ethylene dichloride is heated with. anhydroussodium acetate, under superatmospheric pressure at 230 C. for severalhours, only a trace of reaction occurs. McElroy,

U. 3.. Patent No. 1,259,758, reacted a chlorinated hydrocarbon mixturecontaining ethylene dichloride with calcium acetate in the presence ofaconsiderable quantity of water (i. e. from about 2 to 2.5 parts, byweight, of water for each part of calcium acetate used) to form aproduct containing an ethylene glycol acetate. He states neither theyield nor the purity of the ethylene glycol acetate product, nor does hespecify Whether it is the monoor di-acetate of ethylene glycol which isobtained. We have found that when ethylene dichloride is reacted withcalcium acetate in the presence of water as a solvent, in

a manner similar to that described by McElroy,

the reaction proceeds slowly and ethylene glycol diacetate is obtainedin relatively low yield and 85 intermixed with undesirable by-products,such as ethylene glycol, ethylene glycol monoacetate, etc.,

from which it may be separated only with great difficulty. Water,apparently, hydrolyzes part of the glycol diacetate product under theconditions necessary for reaction.

We have now found that an alkylene dichloride, e. g. ethylenedichloride, propylene dichloride, alphaor betabutylene dichloride,iso-butylene dichloride, etc., may be reacted with an alkali esters. Wehave found, furthermore, that while a solvent, such as alcohol, aceticacid, benzene, toluene, etc., may be employed in carrying out thereaction, the employment of such solvent is unnecessary and that itfrequently interferes with 6 the smoothness of the reaction and purityof the product formed. I

To the accomplishment of the foregoing and related ends, the invention,then, consists of the method hereinafter fully described and particul0larly pointed out in the claims, the following description setting forthin detail several modes of carrying out the invention, such disclosedmodes illustrating, however, but several of the various ways in whichthe principle of the invention may 15 be used.

In preparing ethylene glycol diacetate, for example, according to ourimproved method, an alkali metal acetate is mixed with preferably morethan its chemical equivalent of ethylene di- 20 chloride; one of thepreviously mentioned catalysts is added in amount representingpreferably less than one-tenth of a molecular equivalent of catalyst foreach mole of acetate used, and the mixture is agitated and heated under25 super-atmospheric pressure at a temperature between about 150 andabout 250 C. The reaction, when carried out at 200 C., is usuallysubstantially completed after heating in such manner for from about 1 to2 hours, but longer 0 heating is sometimes required, particularly whenthe reaction is carried out at lower temperatures. The reacted mixtureis then cooled and filtered to remove alkali metal chloride therefrom,and the filtrate is fractionally distilled to separate 5 glycoldiacetate as the substantially pure compound. The catalyst separatedfrom the mixture may be re-employed in the process.

Other alkylene di-esters of aliphatic acids, e. g. butylene glycoldibutyrate, etc., may be prepared 40 through reacting the correspondingalkylene dichloride with an alkali metal salt of the required aliphaticacid in the presence of one of the previouslymentioned catalysts, in amanner similar to that described above.

Through operating according to the above described general method, aglycol di-ester may be formed in excellent yield without simultaneousformation of appreciable quantities of a glycol or a glycol monoesterand the difficulties usually encountered in purifying the diesterproduct through fractional distillation thereof are largely avoided.

The nitrogen-containing catalysts herein described may be employed inamount exceeding 0.1 6

mol. of catalyst per mol. of acid salt, if desired, but ordinarily theemployment of such large quantity of catalyst is unnecessary.

The following table of examples sets forth the yields of ethylenevgylcol diacetate obtained serves as a substantially non-reactivedispersant for the alkali metal salt and permits maintenance of an evenreaction temperature throughout the mixture. The reaction may, however,be carried out successfully, though less conveniently, by

dichloride with an alkali metal salt of'a lower aliphatic acid to formthe corresponding glycol di-ester. g

In practicing our invention we prefer, as illustrated by the specificexamples, to heat'an, alkali metal salt-oi an aliphatic acid with morethan its chemical equivalent of 'an alkylene dichloride. in the presenceof one of thecatalysts herein disclosed, to 'a-temperature between about175 and pressure and at a temperature between about 150 and about 250 C.

3. The method of making an ethylene glycol di-ester' which comprisesreactingethylene di- 5 through reacting ethylene dichloride with sodiumusing equimolecular quantities of the two reactacetate in the presenceof various compounds ants or even by heating the aforementioned alkaliwhich we have found to catalyze the reaction. metal salt with less thanits chemical equivalent As a basis for judging the activity of thecataof. an alkylene dichloride. Again, although the lysts hereindisclosed, the first two runs described reaction proceeds most smoothlyat a temperain the table were made in the absence of a catature betweenabout 175 and about 225 C., it may lyst. Run 2 illustrates the fact thatethylene be carried out successfully at any temperature dichloride maybe heated with sodium acetate, 'in between about 150 and about 250 C.the absence of either a catalyst or solvent, at 200 The presentinvention, in brief, comprises re- C. for as long as 10.5 hours withoutappreciable acting an alkylene dichloride with an alkali metal reactionoccurring. salt of a lower aliphatic acid containing at least It is tobe understood that the examples set two carbon atoms, in the presence ofa catalyst forth in the table are purely illustrative of cerselectedfrom the group consisting of alkylamines, tainways in which theprinciple oi. our invenalkanol-amines, alicyclic amines, pyradine bases,tion may be applied, and are not to be construed and salts of saidamines and bases, to form the as limitations on the invention.corresponding glycol di-ester.

' TABLE 01; EXAM'PLES Reactants Catalyst Reaction conditions Percentyield f ethylene glycol Run No. A diacetate, based ;Gram-mols Gram-moleReaction Reaction on quantity of of ethylene oi sodium Kind Gram-111015temperaperiod sodium acetate dlcloride acetate ture O. hours used 1.21.0 N 115 s Trace. 1.1 1.0 N 200 10.5 Trace. 1.0 1.0Ethylaminehydrochloride--. 0.01 175 6 50 1.0 1.0 Diethylamine.. 0.01 175o 74 1.0 1.0 'Ii'iethylamine 0.01 175 e 72 1.0 1.0 Monoethanolamine 0.01I 175 6 65 1.0 1.0 Triethanolamine 0.01 175 6 85 1.0 1.0 Oyclohexylaminehydto- '0.01 175 6 73 chloride. 1.0 1.0 Pyridine 0.01 175 e 75 1.0 1.0Quinoline o. 01 175 6 85 The principle of our invention may be employedOther modes of applying the principle of our in ways other than thoseset forth in the exinvention may, be employed instead of those ex- 40amples. We have, for instance, reacted propylplained, change being madeas regards the methene' dichloride with sodium acetate to obtain 0dherein disclosed, provided the means stated propylene glycol diacetate;1,2-butylene dichloe by any of the following claims or the equivalentride with sodium acetate to obtain 1,2-butylene of such stated means beemployed. glycol diacetate; ethylene dichloride with sodium We thereforeparticularly point out and dis- 5 propionate to obtain ethylene glycoldipropionate; tinctly claim as our invention: andethylene dichloridewith sodium butyrate to l. The method of making a glycol di-ester rm etylene glycol dibuty l Of Said which comprises reacting an alkylenedichloride actions were carried outin the presence of catawith an alkalimetal salt of a lower fatty acid lysts selected from those previouslymentioned. in the presence of a catalyst selected from the so In placeof a sodium salt of an aliphatic acid, group consisting of alkyl amines,alkanol-amines, the corresponding potassium Salt 3. Potassium alicyclicamines, pyridine bases, and salts of such acetate, potassium propionate,etc.) or, in fact, a ine and ba e any correspondng alkali metal salt ofsuch acid 2. The method of making a glycol di-ester may be reacted withan alkylene (1101 01 e "which comprises reacting an alkylene dichloridepresence f a member of our w a s atawith an alkali metal salt of a lowerfatty acid y ts to f rm t sp d n glycol l st containing at least twocarbon atoms, in the pres- In Place the catalysts Specifically disclosedence of a catalyst selected from the group conin the fo eg d p other yts Suc sisting of alkyl amines, alkanol amines, alicyclic asmonobutylammc. tributy a cy y amines, pyridine bases, and salts of suchamines amine, 2-mtetthivl-cyclolieyxylan;lifiiidethiyzlbne diland-bases,the catalyst being employed in amount amine, trie y amine droc o e,propy aminesulphate, methyl I e hydmbmmide, representing less than 0.1mole of catalyst for butylamine ecetate etc may be employed sum eachmole of thealkali metal salt used and the cessfuny Edpm'mote thereaction of n alkylene reaction being carried out under superatmospherlcchloride with an alkali metal salt of a lower fatty 7o .amines, pyridinebases, and salts of said amines and'bases, the reaction being carriedout under superatmospheric pressure and at' a temperature between'aboutand about 250 C.

4. In a method of making an ethylene glyco di-ester, the step whichconsists in heating an alkali metal salt of a lower fatty acid withethylene dichloride, in the presence of a catalyst selected from thegroup consisting of alkyl amines,- alkanol amines, alicyclic amines,pyridine bases, and salts of said amines and bases undersuperatmospheric pressure to a temperature between about and 225 C.

5. The method of making ethylene glycol diacetate which comprisesreacting ethylene dichloride with an alkali metal acetate in thepresence of a catalyst selected from the group consisting of alkylamines, alkanol amines, alicyclic amines,

pyridine bases, and salts of said amines and bases, the catalyst beingemployed in amount representing less than 0.1 mol of catalyst for eachmol oi alkali metal acetateused and the reaction being carried out undersuperatmospheric pressure and at a temperature between about 150 andabout 6. The method of making ethylene glycol diacetate which comprisesreacting ethylene dichloride with sodium acetate in the presence of acatalyst selected from the group consisting of alkyl amines, alkanolamines, alicyclic amines, pyridine bases, and salts of said amines andbases.

7. The method of making ethylene glycol diacetate which comprisesheating sodium acetate with more than its chemical equivalent ofethylene dichloride, in the presence of a catalyst selected from thegroup consisting of alkyl amines alkanol amines, alicyclic amines,pyridine bases, and salts of said amines and bases, undersuperatmospheric pressure to a temperature between about 150 and about250 C.

8. In a method of making ethylene glycol diacetate, the steps whichconsist in heating sodium acetate with more than its chemical equivalentof ethylene dichloride, in the presence of a catalyst selected from thegroup consisting of alkyl amines, alkanol amines, alicyclic amines,pyridine bases, and salts of said amines and bases, undersuperatmospheric pressure to a tempera- 5 .ture between about 175 and225 C., and fractionally distilling the reaction mixture to separateethylene glycol diacetate therefrom.

9. The method of making a glycol di-ester which comprises reacting analkylene dichloride 10 with an alkali metal salt of a lower fatty acidin the presence of a lower alkyl amine.

10. The method of making ethylene glycol dia'cetate which comprisesreacting ethylene dichloride with sodium acetate-dn the presence of 15 acyclohexylamine, the reaction being carried out under superatmosphericpressure at a temperature between about 150 and about 250 C.

13. The method of making a glycol di-ester which comprises reacting analkylene dichloride 30 with an alkali metal salt of a lower'fatty acidin the presence of a pyridine base.

14. The method of making ethylene glycol diacetate which comprisesreacting ethylene dichloride with sodium acetate in the presence of 35pyridine, the reaction being carried out'under superatmospheric pressureat temperatures between about 150 and about 250C.

' GERALD H. COLEMAN.

GARNETT v. MOORE. 4o

